Fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, as described in U.S. Pat. Nos. 3,683,092 and 3,689,571, is a promising new anesthetic for human use which is essentially non-inflammable, and appears to have few or no undesirable side effects when administered to humans.
In the abandoned U.S. patent application Ser. No. 771,365, filed Oct. 28, 1968, from which the above two patents claim priority, several techniques are suggested which may be used for making ethers having halogen groups in both of the organic ether substituents, including fluoromethylhexafluoroisopropyl ether. It is suggested there that the corresponding alcohol may be reacted with formaldehyde and hydrogen fluoride to form the fluoromethyl ether. However, yields of this reaction generally described in the abandoned patent application cited above, are not of a desired commercial scale, so other, more cumbersome, multiple step synthesis routes were initially preferred. Weynmayr U.S. Pat. No. 2,992,276 also teaches the use of paraformaldehye and hydrogen fluoride as a reagent for synthesizing a fluoromethylether and an alcohol from tetrafluoroethylene.
In accordance with this invention, a simplified, high yield synthesis technique for fluoromethylhexafluoroisopropyl ether is disclosed, capable of producing yields of the desired ether product of the order of 90 percent, with recycling of unused reactants through the reaction mixture for optimization of synthesis. Particularly, fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether may be made this way as a clinical anesthetic on a large scale basis.